Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/12—Bonding of a preformed macromolecular material to the same or other solid material such as metal, glass, leather, e.g. using adhesives
  • C08J5/124—Bonding of a preformed macromolecular material to the same or other solid material such as metal, glass, leather, e.g. using adhesives using adhesives based on a macromolecular component
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
  • C09D183/04—Polysiloxanes
  • C09D183/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D4/00—Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/06—Non-macromolecular additives organic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

Definitions

• This invention relates to an aqueous bonding composition for use in bonding a fluoropolymer material to a substrate
• the aqueous bonding composition contains a silane compound, a water-soluble adhesion-promoting compound, and water
• the present invention provides an aqueous bonding composition that provides improved adhesive bond strength between a fluoropolymer and a substrate. Because a major portion of the solvent component of the aqueous bonding composition is water, the aqueous bonding composition reduces or eliminates the presence of organic solvent within the aqueous bonding composition. Elimination of organic solvent can eliminate the potential harmful effects of such solvent on the environment, and can also eliminate any health and safety concerns otherwise present when using organic solvents.
• Rf— Q-N Z (0 wherein R 1 is hydrogen or a lower alkyl; R f is a surface-tension reducing group such as a fluoroaliphatic group, preferably a perfluoroaliphatic group; Q is a divalent linking group preferably comprising an electron-withdrawing group such as sulfonyl or carbonyl; X is a divalent linking group; and Z is a group that imparts water solubility to the water-soluble surface tension-reducing compound.
• bonded articles comprising a fluoropolymer bonded to a substrate with the above-described aqueous bonding composition.
• the bonded article can be designed for use in various applications.
• the bonded article can be designed for use as a core, support, or insert used in one of various molded seals, such as a shaft seal, a valve stem seal, or a gasket
• Yet another aspect of the present invention relates to a method of improving the adhesive bond strength between a fluoropolymer and a substrate using the above-described aqueous bonding composition
• the method comprises the steps of providing the above-described aqueous bonding composition, providing a substrate and a fluoropolymer, applying the aqueous bonding composition to one or more of the substrate or the fluoropolymer, and applying the fluoropolymer to the substrate to construct a bonded article comprising the fluoropolymer bonded to the substrate
• aqueous as in "aqueous bonding composition” means that a major portion of the solvent component (i e , the non-solid ingredients) of the aqueous bonding composition is water
• the solvent component can be at least 50 percent by weight, preferably 90 percent by weight, and more preferably at least 99 percent by weight water
• the solvent component of the aqueous bonding composition contains no organic solvent, and is 100 percent water
• the present invention provides an aqueous bonding composition that can be used to create or enhance an adhesive bond between a fluoropolymer material and a substrate
• Fluoropolymer materials useful in this invention include fluorine- containing polymers comprising interpolymerized, monomeric units derived from olefinically unsaturated fluorinated monomers.
• vinylidene fluoride also referred to as VF 2 or VDF
• HFP hexafluoropropylene
• TFE tetrafluoroethylene
• CTFE chlorotrifluoroethylene
• the fluoropolymer may also comprise interpolymerized monomeric units derived from fluorine-free olefinically unsaturated monomers, as is known in the fluoropolymer art.
• fluoropolymers can be prepared by methods that are well known in the fluoropolymer art, and that are also described by Kirk- Othmer, Id., at pages 993-5.
• useful fluoropolymers can be prepared by well known high pressure, free-radical, aqueous, emulsion polymerization methods.
• Many useful fluoropolymers are also available commercially. Examples of commercially available fluoropolymers include those available from the Dyneon Corporation of St. Paul Mn.
• FC-2176 FC-2176
• FC-2177 FC-2177
• FE-5640 FE-5642
• FE-5840 FE-5622
• AFLAS fluoroelastomers commercially available from Asahi Glass Co. Japan
• the substrate can be any suitable material useful as a support for a multilayer article comprising a fluoropolymer bonded to the substrate, and that by use of the inventive aqueous bonding composition, can effectively be adhered to a fluoropolymer.
• suitable substrates include inorganic substrates such as metals (e.g , steel, including carbon steel and stainless steel, brass, aluminum, etc ) materials of glass or glass fibers, or one of several known organic materials, such as a polysulfide, polyimide, or KevlarTM.
• the substrate can be other fluoropolymers or fluoroelastomers that are known in the fluoropolymer art to be useful as a substrate, including nitrile rubber, hydrogenated nitrile rubber, epichlorohydrin, EPDM (ethylene-propylene-diene) terpolymer, etc
• the aqueous bonding composition of the present invention can be a solution, dispersion, or mixture containing a silane compound
• the silane compound comprises a hydrolyzable group (e g , alkoxy and/or acetoxy group) and a group that is reactive with the fluoropolymer (a "fluoropolymer-reactive group")
• the fluoropolymer-reactive group can be any of a number of chemical groups that are known in the fluoropolymer art to be reactive with fluoropolymers, including amine groups, diazo groups, mercaptan groups, mercaptide groups, phenoxide groups, etc.
• Preferred fluoropolymer-reactive groups are amino groups, and preferred silane compounds are therefore aminosilanes.
• Useful aminosilane compounds include di- or tri-alkoxy (e.g., methoxy, ethoxy, etc ) or acetoxy silanes having one or two organo groups bonded directly to a silicon atom. At least one of the organo groups preferably comprises a primary amino moiety.
• a class of useful aminosilane compounds is the class of aminosilanes having the general formula:
• R 4 and R 5 are divalent organic moieties such as alkylene, alkenylene, arylene moieties or combinations thereof.
• R 4 and R 5 can generally have from 1 to 10 carbon atoms, and preferably contain from 1 to 4 carbon atoms. Examples of R 4 and R 5 moieties include propylene, ethylene, butylene, oxydiethylene or phenylene moieties
• Examples of useful aminosilane compounds include: 3 -aminopropyltriethoxysilane, N-(2-aminoethyl-)3-aminopropyltrimethoxysilane,
• the aqueous bonding composition can contain one or a mixture of two or more of these or other silane or aminosilane compounds.
• Aminosilane compounds can be prepared by known methods, including those described in "Technical Bulletin Pigments", No. 75, published by the Degussa Corporation, Ridgefield Park, N.J., brochure no. Pig. 75 1-4-1288 DD, issued December 1988, pp. 5-6.
• the silane compound can be present in the aqueous bonding composition in any amount that will provide effective adhesion-promoting properties
• the aqueous bonding composition can comprise from about 0.1 to 10 parts by weight silane compound, more preferably from about 1 to 5 parts by weight silane compound, based on 100 parts of the aqueous bonding composition.
• aqueous bonding composition refers to the water, silane compound, and water-soluble surface tension-reducing compound in the aqueous bonding composition, although it is understood that additional ingredients may also be included within the aqueous bonding composition.
• the water-soluble surface tension-reducing compound allows for increased adhesive bond strength between fluoropolymer and substrate
• One class of preferred water-soluble surface tension-reducing compounds includes compounds comprising a surface tension-reducing group, and a group that imparts water solubility to the surface tension-reducing compound Examples of such compounds can have general formula (1)
• R 1 is hydrogen or a lower alkyl (e g , methyl, ethyl, butyl), preferably hydrogen Rf is a surface-tension reducing group
• Rr groups are monovalent fluoroaliphatic radicals that are stable, inert, non-polar, oleophobic and hydrophobic.
• Rf can be a straight chain, a branched chain, and if sufficiently large, cyclic, or combinations thereof, such as alkylcycloaliphatic radicals Generally Rf can have from 1 to about 20 carbon atoms, preferably from 4 to about 20, and most preferably from 4 to 12 carbon atoms Preferred R
• the Q is a divalent linking group connecting the Rf group to a nitrogen atom
• the Q group can preferably comprise an electron withdrawing group such as a sulfonyl group (-SO -) or a carbonyl group (-C(O)-), and can optionally comprise an electron withdrawing group connected to an alkylene group, wherein the alkylene group is attached to the Rf group
• the Q group can be an alkylene group connected to a carbonyl group (e g , -C 2 H 4 C(O)-), or an alkylene group connected to a sulfonyl group (e g , -CH 2 SO 2 -)
• the divalent linking group X is a divalent linking group between the Z group and a nitrogen atom
• the divalent linking group X can be any of a number of linking groups, such as an alkylene group, or an alkylene group that optionally includes one or more fluorine atoms replacing one or more carbon-bonded hydrogen atoms
• Examples of such divalent linking groups include lower alkylenes (e.g., methylene, ethylene, propylene, butylene, etc.), and fluorinated alkylenes (e.g., fluoromethylene, fluoroethylene, fluoropropylene, fluorobutylene, etc., any of which can be either partially or fully fluorinated).
• Z can be any group that imparts water solubility to the water-soluble surface tension-reducing compound (also referred to herein as a "water-solubilizing group"), and can be any of a number of water-solubilizing groups that are known in the chemical art, including anionic, nonionic, cationic, amphoteric, and amine oxide groups.
• nonionic water-solubilizing groups include alkoxyalkylene groups such as polyoxyalkylene groups (e.g., -(C 2 H 4 O) n -R 6 ) wherein R 6 is hydrogen or a lower alkyl such as methyl or ethyl, and n is an integer greater than 1, preferably in the range from about 3 to 14.
• anionic water solubilizing Z groups include carboxylic acids (COOH), carboxylate salts (COO " M + , wherein M + can be a suitable counterion such as ammonium or a metal ion; e.g., K + , Na ⁇ Li + , NH , N(R 7 ) 4 + etc., and wherein each R 7 is independently a lower alkyl), sulfonic acids or sulfonic salts (-SO 3 H or -SO 3 " M + , wherein M" is as previously defined), phosphonic acids or phosphonic salts (-HPO 3 or -PO 3 M + , wherein M * is as previously defined), etc.
• Preferred water-soluble adhesion-promoting compounds include fluoroaliphatic sulfonyl compounds including the following: wherein M ⁇ is a suitable counterion as defined above. These fluoroaliphatic sulfonyl compounds can be used singly or together as a mixture of two or more of these or other water-soluble surface tension-reducing compounds.
• the water-soluble surface tension-reducing compound can be present in the aqueous bonding composition in an amount that will provide a useful wetting of the substrate, and effective adhesion between the substrate and the fluoropolymer.
• water-soluble it is meant that the adhesion-promoting compound will dissolve sufficiently in the aqueous bonding composition, without the aid of a substantial amount of organic solvent, to provide an aqueous bonding composition of a useful surface tension and that will provide effective adhesion between the substrate and the fluoropolymer.
• the concentration of the water-soluble surface tension-reducing compound required to provide a desired surface tension and level of adhesion will be a function of: the particular water-soluble surface tension-reducing compound used; the identity and amounts of other components of the aqueous bonding composition, such as the silane compound; and the particular fluoropolymer and substrate desired to be bonded together.
• the water-soluble surface tension-reducing compound is preferred present in such a concentration that the surface tension of the aqueous bonding composition be lower than 50 millinewtons per meter, more preferably below 30 millinewtons per meter, at a concentration of 0.1 percent by weight.
• Surface tension can be measured by methods that are known in the chemical art, such as by the DuNuoy Ring method
• the surface tension reducing group should not be present in an excessive amount, e g , an amount that would result in excessive foaming
• some water-soluble surface tension-reducing compounds have been found to be effective at concentrations in the range from about 0 05 to 5 parts by weight, based on 100 parts aqueous bonding composition
• Preferred concentrations of the water-soluble surface tension-reducing compound can be in the range from about 0 1 to 1 parts by weight, based on 100 parts aqueous bonding composition, with the range from about 0 1 to 0 5 parts by weight being especially preferred
• Water-soluble surface tension-reducing compounds can be prepared by known methods
• water-soluble fluoroaliphatic sulfonamide compounds can be prepared by the reaction of ammonia or primary amines with perfluoroalkane sulfonyl fluorides (sulfonyl fluorides can be obtained, e g , by electrochemical fluorination of alkyl or alkylene sulfonyl halides)
• Methods of preparing sulfonyl fluorides, as well as fluoroaliphatic sulfonamide compounds are described, for example, in U.S Patent Nos 2,732,398 (Brice et al), 2,759,019 (Brown), 2,809,990 (Brown), 2,915,554 (Ahlbrecht), and 3,094,547 (Heine)
• water-soluble fluoroaliphatic carboxamide compounds are known in the chemical art, and can be prepared by known methods including the reaction of a perfluoroalky
• substrate surfaces Before being coated with the aqueous bonding composition, substrate surfaces can be prepared using conventional methods such as those described in Davis, D J. and Kosmala, J.L , "A Practical Approach to Fluoropolymer Adhesion to Metal", presented at the Energy Rubber Group Adhesion Symposia, Houston, Texas, May 30, 1985, and the "Chemlok® 607" brochure no DS 10-6005J, published by the Lord Corporation in 1981
• nonmetallic substrate surfaces can be thoroughly cleaned using an appropriate solvent Glass may be cleaned using an alkaline bath
• the preparation of metallic substrates depends to some extent upon the type of metal However, where roughening of the substrate surface is desired, the substrate can first be degreased using a suitable solvent such as trichloroethylene or Stoddard Solvent, then sandblasted (e g , using 40 to 60 mesh alumina grit), and then the sandblasted surface can again be degreased Alternatively, or in addition to other treatments, metal substrates can be phosphatized (
• the substrate can be designed such that when bonded to a fluoropolymer, the bonded multilayer article will be useful as a core, support, or insert, used in one of various molded seals, such as a shaft seal, a valve stem seal, or a gasket.
• the fluoropolymer can be bonded to the substrate by methods that are known in the fluoropolymer art, for instance by compression molding, transfer molding, or injection molding, etc.
• Sample shaft seals were prepared in accordance with the present invention. Fluoropolymer used to prepare seal shaft Samples A and B are described in Table 1 , which reports parts by weight of ingredients of the fluoropolymer.
• Shaft seal Samples A and B were produced by injection molding the fluoropolymer onto a metal (carbon steel) ring support substrate having the following dimensions.
• the metal ring supports for the shaft seals were prepared by degreasing the metal ring supports by manually wiping off any excess oil, followed by rinsing with perchlore ethylene, and evaporative drying while lying on a paper towel
• the ring supports were then placed in a caustic bath at 70°C to 80°C for 8 to 10 in The caustic bath was a 5 weight percent solution of Extran AP 12 alkaline from Merck dissolved in hot (70 to 80°C) deionized (DI) water After the caustic bath, the ring supports were rinsed three times in cold DI water
• the degreased metal ring supports were phosphatized according to the following procedure
• the degreased ring supports were taken from the last rinsing bath and placed in a phosphatizing bath of a 2% by weight solution of 758 g ZnO, 1.89 liter H 3 PO 4 (75% by weight in water), and 1 89 liter DI water
• NaNO 2 was added as a 25% solution to give a concentration of about 0 02wt% NaNO 2 in the bath
• the temperature of the bath was maintained at 75-80°C and stirred, and the ring supports were submersed for 8 to 10 minutes
• the phosphatized ring supports were rinsed three times in cold DI water and dried in a 75°C forced air oven for 8 to 10 minutes
• a fresh solution was prepared, and the rinsing baths were filled with fresh DI water
• the dry ring supports were stored in a closed plastic container Next, the aqueous bonding composition was applied to the degreased
• a stock solution was made by dissolving 25 01 grams of 3-(triethoxysilyl)- propylamin in DI water and diluting with DI water to a total of 500 0 grams This 5% solution was the reference aqueous bonding agent Aqueous Bonding Agent 1 (BA-1) was prepared by adding 99 grams of the above stock solution to 1 01 grams of a 30%(wt) in water solution of C 8 F , 7 SO 2 NH(CH 2 ) 3 NO(CH 3 ) 2 .
• Aqueous Bonding Agent 2 (BA-2) was prepared by adding 99 grams of the stock solution to 1.00 grams of a 30%(wt) in water solution of C 6 F 13 SO 2 NH(CH 2 ) 3 NO(CH 3 ) 2
• Aqueous Bonding Agent 3 (BA-3) was prepared by adding 99 grams of the above stock solution to 1.01 grams of a 30%(wt) in water solution of C 8 F 17 SO 2 NH(CH 2 ) 3 COOK.
• Fluoropolymer A proved very difficult to demold, and there was a tendency to disrupt the bond during the automatic demolding.
• one indication of bond strength was the number of Samples that survived the automatic hydraulic ejection from the mold, without the fluoropolymer delaminating from the metal ring support.
• Table 4 describes the amount of fluoropolymer, in percent, which remained on the ring support after automatic hydraulic ejection from the mold, for each of the four bonding agents.
• Table 4 shows a significant improvement in adhesion for bonding agents 1 , 2, and 3, over the reference aqueous bonding agent.
• Fluoropolymer B showed good demolding behavior and also good bond strength between the fluoropolymer and the metal ring support. Ten Samples were prepared for each bonding agent.

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